The invention relates to a trailer for hauling elongated objects, particularly a trailer for towing behind a 3 or 4 wheeled recreational all-terrain vehicle, or a recreational snow vehicle for "skidding" logs from a relatively small forestry harvesting operation.
It is known to skid logs behind heavy duty industrial tractors, commonly called "skidders", which are large articulated rubber-tired vehicles. Such vehicles are costly to operate, and being relatively large require some considerable space for maneuvering, and thus are only appropriate in relatively large "clear-cut" logged areas. Such vehicles are relatively heavy and powerful and can inflict considerable topsoil damage to clear-cut areas, which can present difficulties with more stringent environmental controls that are becoming common for industrial logging operations. Such vehicles are too large, lack maneuverability, and inflict too much damage to the top soil for use in environmentally sensitive "selective logging" or "high retention logging" operations where a large percentage of trees remain standing after logging, and the skidding vehicle must manoeuvre around the standing trees. Prior to industrial clear-cut logging, horses were often used to skid the logs from selectively logged areas, and this caused less environmental damage than the modern heavy industrial equipment used in the clear-cut areas.
When skidding logs it is necessary to lift a forward portion of the log above the ground to avoid the forward portion "digging in" and thus increasing resistance to skidding as well as damaging top soil. With heavy logs, considerable force is required to lift the forward end of the log, even though much of the weight of the log is carried by the rear end of the log in contact with the ground. Various apparatus, e.g. wheeled carriages etc. for skidding logs have been devised, some of which were designed for pulling by horses, whereas others were designed for pulling by motorized vehicles. Such carriages must be ruggedly designed to withstand handling heavy loads combined with indeterminate impact forces from traversing rough terrain, but clearly an excessively heavy carriage detracts from the payload that can be carried. Consequently, the carriage must be an efficient lightweight and strong structure which is sufficiently strong to withstand unpredictable impact forces occurring during use without being so heavy that payload is reduced excessively.
U.S. Pat. No. 2,452,338 (Thompson) discloses a logging cart having a single main tongue extending forwardly from an inverted U-shaped arched axle supporting a pair of wheels. Rigid side bars serve as diagonal braces extending forwardly from lower frame portions above the wheels to connect with the main tongue. A log is supported with a length of chain extending between the wheels and a length of chain adjacent the side bars. The side bars are rigid and thus would interfere with bulky loads and thus limit the width of loads that can be carried. In addition, the side bars are prone to damage during use, and because they are rigid, if they were badly damaged they might twist or "skew" the arched axle so that the wheels become non-aligned with the tongue, thus aggravating wheel wear, top soil damage and increasing pulling loads.
U.S. Pat. No. 819,385 (Strange) discloses a logging cart in which a vertical inverted U-shaped frame carrying wheels is connected to a horizontal U-shaped frame which is towed behind the vehicle. A pair of chains extends from positions adjacent the wheels to a rear end of the log to relieve load from the log on the support. In applicant's opinion, supporting a heavy log in such a structure would likely result in excessive lateral swinging movement of the log relative to the structure, causing erratic loading for the towing vehicle with a risk of unintentional interference of the log with the structure or adjacent obstructions.
U.S. Pat. Nos. 572,742 (Carroll) and 2,679,329 (Stout) disclose wheeled carriages with levering devices for lifting elongated loads.